Such electric motors, having a stator and a rotor, are known from the prior art, wherein the rotor has a rotor position magnet, realized in the manner of a magnet ring, for acquiring a rotational speed signal. This magnet is fastened to a rotor shaft of the rotor in a rotationally fixed manner. For the purpose of compensating imbalance of the rotor, material is removed from defined positions on the rotor, e.g. on the rotor position magnet.
A disadvantage of this prior art is that, as a result of removal of the material from the rotor position magnet, cracks may occur on the magnet, or parts of the magnet may drop off, owing to the brittleness of the magnetic material. Cracks that occur in such a manner may result in a reduction in the functional capability of the electric motor. Moreover, during such a removal of material, swarf may be produced, which has to be elaborately removed from the rotor.